Cloudformation is for when you have a team of ops or a workflow where you have a lot of repeated resource recreation; Beanstalk is for when you have no ops, and you're happy for someone else to handle the environment; CodeDeploy is just yuck; and don't know about this one yet.

    Cloudformation: infrastructure-as-code (but has sharp edges) (doesn't touch your app/code directly)
    Opsworks: wizard-style 'drop your app here' kind of thing (less flexibility and control)
    Beanstalk: a simpler version of OpsWorks? (never tried it)
    CodeDeploy: install an agent, it pulls code/artifacts (janky workflow)
    CodeBuild: no idea, just been released
    Just Using The Web Console: convenient, but manual process (labour-intensive, prone to manual errors)

On the CI thing - from my experience at one of the places I work, there are a thousand CI systems out there, but very few CD systems. Pretty much anything can schedule and track builds, but few things schedule and track deploys (which gets suprisingly tricky suprisingly quickly). CD is the 'last mile'...

EDIT: missed some that I've never looked at. It is getting crazy...

    CodeCommit: looks like it might be a 'github'?
    CodePipeline: No idea. Perhaps a spruced-up version of CodeDeploy?

I appreciate the breakdown. It would be awesome if there was someone with the know-how to go more in depth on each of these.

I recently inherited an app that uses OpsWorks. The deploy process is actually really nice, but I notice that it doesn't receive a lot of updates from AWS. Since OpsWorks came out when Chef was hot, and now Chef seems to be less popular than Ansible and/or docker. I wonder what the future holds for me if Chef continues to decline in popularity.

This was my thought as well. I've seen them offer a few different of these "workflow engines" that seemed to be quite clearly oriented towards build services, although this is the first that's very explicitly focused on that.